Method of and an apparatus for measuring surface contour

ABSTRACT

A measurement-datum similar to profile of a measuring object set in a measuring area in which a detector and the measuring object are moved relatively is formed to measure the displacement value between the detector and the measuring object through the relative movement based on the measurement-datum to thereby compute the surface contour of the measuring object from the measured data with reference to the measurement-datum. Since the measurement-datum is set in the spatial area, a precise mechanical processing will not be required for an accurate measurement of the measuring object having a strange profile which was not measured by conventional apparatus.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention broadly relates to a method of and an apparatus formeasuring a surface contour of a measuring object by relatively moving adetector and the object and, more particularly, a method and anapparatus to be used to grasp an outline of the measuring object byrelatively moving the detector, such as a non-contacting or contactingtype detector, and the measuring object to measure the surface contourof the measuring object with or without keeping a contacting statetherebetween, when measuring a right-angled, round-shaped, ellipticalprofile or a profile combining them all together.

2. Description of the Related Art

An instrument as diagrammatically depicted in FIG. 14 has previouslybeen used to measure a surface contour of an object to be measured.Reference numeral 1 in the drawing is a base for supporting a verticalcolumn 2 thereon. The column 2 has slidably guided, thereon an elevationdevice 3 movable in an up-and-down direction (Z-direction) by means of anot-shown feed screw. The elevation device 3 has therein a pivotalmovement system 4 pivotal by a certain angle (θ) about an axis extendingperpendicularly to the vertical axis of the column 2 (an axisintersecting the drawing depicted in FIG. 14. The pivotal movementsystem 4 has a feed screw 6 adapted to be rotated by a motor 5A or amanually operated handle 5B.

The feed screw 6 is provided via a connection member 7 such as a nut toreciprocally carry a detector 8 in a right-and-left direction(X-direction) in the drawing. The detector 8 has a measuring arm 10 witha stylus 9 at the forward end in a state to move up-and-down pivotallyand a displacement value detecting sensor (not-shown) such as a linervoltage differential transformer (LVDT) to electrically detect apivoting degree of the measuring arm 10. Incidentally, a memberdesignated by the reference numeral 2A is a manually operated handledesigned to effect a movement of the elevation device 3 verticallyup-and-down (Z-direction).

When conducting a measurement with this measuring apparatus, themeasuring object W is first located on the base 1 and the stylus 9 isthen moved to a point on the upper surface of the measuring object Wwhere the measurement begins. The detector 8 is moved reciprocally inthe X-direction corresponding to the rotation of the feed screw 6 by themotor 5A. As the detector 8 moves into the X-direction, the stylus 9 ofthe measuring arm 10 tosses in response to the surface irregularities ofthe measuring object W. The movement of the measuring arm 10 is detectedby the displacement value detecting sensor (not-shown) to measure thesurface contour of the measuring object W.

As can be understood from the above-descriptions, the conventionalsurface contour measuring apparatus is naturally adapted to regard therectangular coordinates defined by the base 1 and the column 2 asmeasurement-datum, so that the mechanical accuracy of the apparatus isalways a main factor of accuracy in measurement. The flatness of thebase 1, the straightness of the movement of the detector 8 with themeasuring arm 10 and the displacement value detecting sensor, and theverticalness of the column 2 against the base 1 should be a main factorof accuracy in measurement. Accordingly, the conventional machinerequires a high order of accuracy in assembling and adjusting it andalso a great deal of time in maintenance.

When a contacting detector will be used, a stylus thereof may cause thesame problem because the radius of the stylus may involve an error, sothat some compensation means for the radius error is inevitably to beprovided. The error of the radius should influence unnecessarily ameasurement signal referencing the Z-direction or the X-direction. Thiswill be remarkable when requiring a high order of accuracy. It is knownthat, in the non-contacting type detector, an optical axis of thedetector should be aligned with a normal axis of the surface of themeasuring object as much as possible to achieve the high order ofaccuracy. However, the conventional apparatus could not shift itsposture preferably corresponding to the irregularities of the measuringobject to execute a preferable measurement.

The possible measuring range along the X-direction coordinate axis canbe extended whereas that of the Z-direction coordinate axis will belimited. Accordingly, the measuring object was limited to be a flat one,so that other ones having a right-angled, round-shaped, ellipticalprofile or a profile combining them all together could not be measuredeasily.

If it will be required to conduct the surface contour measurement withthe conventional apparatus, the measuring object is generally tiltedbefore measurement. But, the measuring range tends to be narrow in spiteof having enough measuring range in the X-direction.

In a circularity test, the measuring object is rotated throughmeasurement while maintaining a coaxial alignment of the measuringobject and the rotation device to rotate the measuring object. Thisalignment work is a time-consuming one and requires much skill. In thismeasurement, the measuring range or capacity is also limited as in themethod which is done by tilting the measuring object. Accordingly, if weneed to measure a surface contour of the measuring object, suchconventional apparatus was not available to obtain the necessary data.

The object of the present invention is to solve such problems withoutrequiring a precise mechanical processing and adjustment to conductprecise surface contour measurement to thereby provide a method and anapparatus capable of measuring any measuring surface which was notmeasured by the conventional apparatus.

SUMMARY OF THE INVENTION

Accordingly, a method according to the present application is the methodof measuring a surface contour of a measuring object by a surfacecontour measuring apparatus having a displacement system for relativelymoving a detector and the measuring object, the method comprising thesteps of: originating measurement-datum which is an outline similar to aprofile of the measuring object put in a measuring area in which thedetector and the measuring object move relatively; measuring adisplacement value between the detector and the measuring object bymoving the detector and the measuring object relatively in accordancewith the originated measurement-datum; and computing surface contour ofthe measuring object in accordance with the measured displacement value.

When originating the measurement-datum, the method may further comprisethe step of: originating and memorizing compensation data to compensatea gap between a spatial coordinate axes made in the measuring area and amechanical coordinate axes of the displacement system after putting inthe measuring area a measuring standard of which surface contour isprecisely understood, moving the measuring standard and the detectorrelatively to actually measure surface contour or position data of themeasuring standard, and thereafter making the spatial coordinate axesbased on the measured relative position of the detector and themeasuring standard, so that the originated measurement-datum or themeasured displacement value data is corrected based on the compensationdata when originating measurement-datum or computing surface contour ofthe measuring object.

Incidentally, the measuring standard is a right angled measuringstandard of which surface contour is precisely understood and thespatial coordinate axes may be a rectangular spatial coordinate axes.

The step of originating measurement-datum may include preliminarilymeasuring a displacement value between the detector and the measuringobject by moving the detector and the measuring object relatively withinthe measuring area and to originating a relative movement locus similarto a profile of the measuring object in the measuring area as themeasurement-datum in accordance with the preliminary measureddisplacement value.

The step of originating measurement-datum may include to preliminarilymeasure a displacement value between the detector and the measuringobject through the relative movement thereof and to generate relativemovement locus as to set a relative movement locus having a similarshape to the measuring surface of the measuring object and beingcompensated by a compensation data obtained through the compensationdata originating step based on the measurement data obtained through thepreliminary measurement step, as the measurement-datum in the measuringarea. Incidentally, the measuring object is located at a predeterminedplace by a fixture in the measurement step and preliminary measurementsteps. And, the preliminary measurement step is to relatively move themeasuring object and the detector in accordance with a movement locus ofthe detector.

A surface contour measuring apparatus according to the present inventionis to comprise a table for mounting thereon a measuring object; adetector mounting member; a movement system for relatively moving thetable and the detector mounting member in a X-direction and in aZ-direction perpendicular to the X-direction; a rotating table rotatingrelatively to the detector mounting member about a pivot extending in adirection perpendicular to the X- and Z-directions; a detector providedon the rotating table to detect, as an electric signal, a distance froma measuring surface of the measuring object located within a detectablearea of the detector; and a computing device having a memory means forstoring therein data regarding measurement-datum similar to profile ofthe measuring object in a spatial area in which the table and thedetector move relatively, a measuring means for measuring a displacementvalue of the detector and the measuring object through the relativemovement of the detector and the measuring object in accordance with themeasurement-datum, and a contour computing means for obtaining thesurface contour of the measuring object based on the measured data inthe measuring means to thereby formulate a surface contour of themeasuring object in accordance with output from the detector.

Incidentally, the movement system is defined by a X-axis drive means formoving the table in the X-direction, a Y-axis drive means for moving thetable in the Y-direction perpendicular to the X- and Z-directions, and aZ-axis drive means for moving the detector mounting member. The X-axisdrive means, the Y-axis drive means and the Z-axis drive means includefeed screws and motors to rotate the feed screws.

The detector should be a non-contacting type and is located to have adetectable area including the central axis of the pivot. The detectorpreferably has a light source, an optical system including an objectglass to apply light from the light source on the measuring surface, adetecting circuit issuing signal corresponding to a difference betweenthe focal point of the object glass and the measuring surface, a drivingsystem for moving the object glass to coincide the focal point of theobject glass with the measuring surface, and a position detecting meansfor detecting a position of the object glass.

And the memory means is adapted to memorize, as compensation data, thedifference between a mechanical coordinates based on the movement systemand a spatial coordinates determined based on a relative positionalrelationship between a measuring standard and the detector, and thecomputing device further includes a means for compensating themeasurement-datum with reference to the compensation data store in thememory means.

The computing means may further include a means for controlling thedrive means to move the detector and the measuring object relatively inaccordance with the measurement-datum stored in the memory means.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an overall composition in the firstembodiment in accordance with the present invention;

FIG. 2 is a perspective view of a measuring apparatus in the firstembodiment;

FIG. 3 is a vertical sectional view of a main body of the measuringapparatus;

FIG. 4 is a sectional view depicting a non-contacting type detector hefirst embodiment;

FIG. 5 is a block diagram of an electrical circuit in the firstembodiment;

FIG. 6 is a flowchart depicting a process for originating compensationdata in the first embodiment;

FIG. 7 is an operational view depicting how a measuring standard ismeasured in the first embodiment;

FIG. 8 is a view of originated measurement-datum within a measuring areain the first embodiment;

FIG. 9 is a flowchart depicting a measurement process in the firstembodiment;

FIG. 10 is a perspective view depicting a setting jig for the measuringobject in the first embodiment;

FIG. 11 is a view for explaining a movement locus of the detector in apreliminary measurement of the measuring object;

FIG. 12 is a view for explaining a movement locus of the detector in amain measurement of the measuring object;

FIG. 13 is a view of originated measurement-datum when measuring anotherprofile (sine-curve) different from the first embodiment; and

FIG. 14 is a diagrammatic view depicting a conventional surface contourmeasuring apparatus.

Certain terminology will be used in the following description forconvenience in reference only and will not be limiting. The words "up","down", "right" and "left" will designate directions in the drawings towhich reference is made. The words "in" and "out" will refer todirections toward and away from, respectively, the geometric center ofthe device and designated parts thereof. Such terminology will includederivatives and words of similar import.

Still other objects and advantages of the present invention will becomereadily apparent to those skilled in this art from the followingdetailed description, wherein only the preferred embodiments of theinvention are shown and described, simply by way of illustration of thebest mode contemplated of carrying out the invention. As will berealized, the invention is capable of other and different embodiments,and its several details are capable of modifications in various obviousrespects, all without departing from the invention. Accordingly, thedrawing and description are to be regarded as illustrative in nature,and not as restrictive.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The preferred embodiment of the present invention will now be describedwith reference to the drawings.

FIG. 1 depicts the overall composition of a system for measuring asurface contour of a measuring object according to the first embodiment.This system is defined by a main body of the measuring apparatus A formeasuring the measuring object put thereon, a computing device B tocontrol the measuring apparatus A and to store the measured data, and adata analysis processing unit(host-computer) C to analyze the measureddata sent from the computing device B and to display the resultthereafter. The designation D is a table.

The measuring apparatus A comprises, as shown in FIGS. 2 and 3, a base11, a X-axis table 13 reciprocally movable on the base 11 by means of aX-axis drive means 12, a Y-axis table 15, moving in the Y-direction onthe X-axis table 13 by means of a Y-axis drive means 14, for supportingthereon a measuring object 101, a column 16 standing behind the base 11,a Z-axis slider 18 vertically and slidably moving on the column 16 inthe Z-direction by means of a Z-axis drive means 17, a turn table 20mounted on the Z-axis slider 18 rotatably about an axis parallel to theY-axis by means of a rotation drive means 19, and a non-contactingdetector 21 located over the turn table 20 so as to keep thepredetermined detection area. Incidentally, a movement system 10 forrelatively moving the non-contacting detector 21 and the measuringobject 101 is defined by the tables 13, 15 and 20, the Z-axis slider 18and the drive means 12, 14, 17 and 19. The coordinate movement into theX-, Y- and Z-directions can be performed by the table 15 having themeasuring object 101 thereon and the Z-axis slider 18 for supporting thedetector thereon.

The base 11 is provided with plural switches 22 on a switch panel 23attached at the front side thereof. The X-axis drive means 12 and theY-axis drive means 14 is defined by feed screws 24X, 24Y and motors 25X,25Y in a cover 26 secured on the base 11. The Z-axis drive means 17 isdefined by a feed screw 27 rotatably provided in the column 16 in astate parallel to the Z-axis, a motor 31 related with the feed screw 27via a speed reducer 28 and a helical gears 29, 30, and a nut member 32received on the feed screw 27 and secured on the Z-axis slider 18. Therotation drive means 19 is defined by a pivot 34 extending in theY-direction from the Z-axis slider 18 through a box 33 to receive theturn table 20 at its forward end, and a motor 37 rotating the pivot 34via the helical gears 35, 36. The designation 38 is a balance weightconnected to one end of a wire 40 of which the other end is connectedvia a block 39 over the column 16 with the Z-axis slider 18. Thedesignation 41 is a dustproof bellows to cover the front of the column16 when the Z-axis slider 18 reciprocally moves up-and-down and thedesignation 42 is a cover.

An example of the non-contacting detector 21 is depicted in FIG. 4. Inthis drawing, the reference numeral 60 indicates a semiconductor laseras a light source, 61 indicates a polarizing beam splitter to reflectthe light from the semiconductor laser 60 to a measuring surface of themeasuring object, 62 indicates a collimator lens for regulating thelight reflected at the polarizing beam splitter 61 into parallel beams,63 indicates an object glass, and 64 indicates a 1/4-wave plate for ahigh efficiency with a combination with the polarizing beam splitter 61compared with a half-mirror. The reference numeral 65 is animage-formation lens for imaging the reflecting light passing throughthe beam splitter 61, 66 is a beam splitter for dividing the lightpassed through the image-formation lens 65. 67A and 67B are pin-holeplates located before and behind the focal points of the divided lightby the beam splitter 66. 68A and 68B are light-interception elementssuch as photo-diodes for detecting luminous energy passed through thepin-hole plates 67A and 68B. and 69 is a detection circuit to receiveoutput signals from both light-interception elements. Incidentally, animage-formation optical system 70 is defined by the beam splitter 61,the collimator lens 62, the object glass 63, the 1/4-wave plate 64, andthe image-formation lens 65.

The object glass 63 is mounted at a forward end of a movable lens-barrel72 which is movable vertically in the main body of the measuringapparatus 71. There are provided, between the main body 71 and themovable lens-barrel 72, a drive system 73 to shift the movablelens-barrel 72 up-and-down and an encoder 74 as a position detectingmeans for detecting an actual vertical position of the movablelens-barrel 72 or the object glass. The drive system 73 is defined by amagnet 73A secured to the main body 71 and a moving coil 73B such as avoice-coil provided on the movable lens-barrel 72. The encoder 74 isdefined by a scale 74A related to the movable lens-barrel 72 and adetector 74B secured to the main body 71 to oppose the scale 74A.

When applying a beam light of the semiconductor laser 60 to the surfaceof the measuring object through the beam splitter 61, the collimatorlens 62 and the object glass 63, the reflected light from the measuringobject is divided by the beam splitter 66 and separately received in thelight-interception elements 68A, 68B through the pin-hole plates 67A,67B. In the detection circuit 69, dividing the difference of outputsignal between two light-interception elements 68A and 68B by the sum ofoutput signals of the light-interception elements 68A and 68B, aS-shaped focus error signal setting a gap between a focal point of theobject glass 63 and the measuring surface can be obtained. The drivesystem 73 is activated to adjust the focal point of the object glass 63on the measuring surface based on the S-shaped focus error signal, andan output from the encoder 74 will be utilized to detect theirregularities of the measuring surface. In this embodiment, an actualluminous energy at a point along the beam light axis near the focalpoint is continuously detected from the beam light and the reflectedlight of the same. At the same time, the object glass is shifted so thatthe focal point is adjusted on the surface of the measuring object,which distance is regarded as the irregularities of the measuringsurface. Incidentally, the focal point is adapted to be made on thecentral axis of the pivot 34. In other word, the detector 21 is providedso that the measuring area thereof always contains the central axis ofthe pivot 34. The used detector 21 has a capacity to move by 10millimeters, a measuring range from 600 to 6 micrometers, and aresolution from 0.2 to 0.002 micrometers.

FIG. 5 is a block diagram depicting a circuit between the main body ofthe measuring apparatus A and the computing device B. The computingdevice B comprises a CPU 51, a transmission portion 52, a memory portion53 as a memory means, a preamp portion 59, a data sampling portion 54, aswitches control portion 55, a motor driver portion 56, a counterportion 57 and a bus 58 to connect therebetween. The CPU 51 is providedfor processing data based on a prepared processing program stored in thememory portion 53, of which detail steps will be explained in anexplanation of the operation. The transmission portion 52 connects tothe data analysis processing unit C. The memory portion 53 further hasother memory capacity such as a measurement map storing area memorizingvarious measurement maps, a datum storing area memorizing data oforiginated measurement-datum, a compensation data storing areamemorizing compensation data, a data storing area memorizing inputtedmeasurement-data, and the like.

The preamp portion 59 receives outputs from the non-contacting detector21 synchronizing with the data sampling portion 54 to get the outputs atpredetermined intervals. The data sampling portion 54 is adapted toreceive outputs from preamplifiers 49X, 49Y, 49Z or 49θ selectively atpredetermined sampling intervals. The switches control portion 55receives data from the switches 22. The motor driver portion 56 connectswith motors 25X, 25Y, 31 and 37 for the drive means 12, 14, 17 and 19.The counter portion 57 receives outputs from the encoders 45, 46, 47, 48detecting displacement values of the drive means 12, 14, 17, 19 throughthe preamplifiers 49X, 49Y, 49Z, 49θ.

The encoder 45 which detects a displacement value in the X-direction hasa X-axis scale attached on the X-axis table 13 along the X-direction anda detector secured on the base 11 so as to oppose the X-axis scale witha certain spacing therebetween. The encoder 46 which detects adisplacement value in the Y-direction has a Y-axis scale attached on theY-axis table 15 along the Y-direction and a detector secured on thetable 13 so as to oppose the Y-axis scale with a certain spacingtherebetween. The encoder 47 which detects a displacement value in theZ-direction has a Z-axis scale attached on the column 16 along theZ-direction and a detector secured on the Z-axis slider 18 so as opposeto the Z-axis scale 13 with a certain spacing therebetween. The encoder48 for detecting a rotating angle θ of the non-contacting detector 21comprises a rotatable disc secured to the pivot 34 and a detectorsecured to the box 33 so as to oppose the rotatable disc with a certainspacing therebetween.

The above apparatus in this invention facilitates an operative sequenceas will be explained in more detail below with reference to FIGS. 6-12.

First, a measuring standard such as the right-angled measuring standardis set in the measuring area (=a relative movement area between thedetector 21 and the measuring object) created by the movement system 10before shipment. The profile and position of the measuring standard ismeasured in a relative movement of the measuring standard and thenon-contacting detector 21, whereby spatial coordinate axes areoriginated. The difference between the spatial coordinate axes and themechanical axes depending upon a mechanical precision of the movementsystem 10 is written in the memory portion 53 as the compensation data.

These steps are shown in a flowchart of FIG. 6. In step 1 (hereinafterreferred to as ST 1), an origin for measurement is detected. In ST2, themeasurement standard is then measured.

Taking for an instance, after a measurement standard 100 is set in themeasuring area, the non-contacting detector 21 follows the moving tracks(1) down-loaded from the data analysis processing unit C whichpreliminarily sets and memorizes the moving tracks (1) for theright-angled profile of the standard 100 before measurement. In thismovement, the measured data from the non-contacting detector 21, or thedisplacement value between the non-contacting detector 21 and themeasuring standard 100 is obtained at predetermined intervals.

When measurement of the standard is finished, in ST3, rectangularspatial coordinates, as a datum of the measuring apparatus, of X' and Z'as shown in FIG. 8 is originated in the measuring area based on therelative position of the detector 21 and the standard 100 afterobtaining the sample data. Furthermore, the compensation data as thedifference between the rectangular spatial coordinates and themechanical X-Z coordinates depending upon the mechanical precision ofthe movement system as shown in FIG. 8 is prescribed. In ST4, thecompensation data is written in the memory portion 53.

The main measurement will be conducted following a flowchart shown inFIG. 9. In ST11, the apparatus is initialized and the origin isdetected. In ST12, the prepared measurement map is down-loaded from thedata analysis processing unit C. If the measuring object has aright-angled portion, a measurement map for movement locus of therectangular spatial X'-Z' coordinated (datum for the apparatus) will bedown-loaded. If the right-angled portion of the measuring object 101 isthat as shown in FIG. 11, the X'-axis (2) and the Z'-axis (3) are setwith reference to the measuring object 101. Incidentally, the measuringobject 101 is set by positioning tools 111, 112 on a fixture 110 in themeasuring area, the positioning tool 112 moving in a dotted-line whensetting the measuring object and locating at the solid line inmeasurement.

In ST13, a preliminary measurement for the measuring object 101 isconducted. In measurement, as shown in Figure 11, the non-contactingdetector 21 and the measuring object 101 are relatively moved along themovement locus (2) by the measuring map. The data measured by thenon-contacting detector 21 is recorded at predetermined intervals.Furthermore, the non-contacting detector 21 and the measuring object 101are relatively moved along the movement locus (3) by the measuring map.The data measured by the non-contacting detector 21 is recorded atpredetermined intervals.

In ST14, a measurement-datum similar to the surface contour of themeasuring object is originated in the measuring area. A turning centerof the detector 21 is determined based on the measured data whenfollowing the moving locus (2), (3). In other words, rotation centercoordinates P for the detector 21 are decided to obtain a circular arc(5) as shown in FIGS. 11 and 12 in a state that the normal direction ofthe measuring object and the optical axis of the non-contacting detector21 are coincided and that the distance between the measuring surface andthe non-contacting detector 21 is within a detectable area of thedetector. Accordingly, a relative moving locus (4) defined by theX'-axis, the circular arc (5) and the Z'-axis is originated as shown inFIG. 12. The data of the relative moving locus (4) is corrected by thecompensation data and recorded in the memory portion 53 as themeasurement-datum.

In ST15, the main measurement for the measuring object 101 is done. Atthe beginning of the main measurement, while the measuring object 101 iskept in the same state, the detector 21 returns to the start point formeasurement automatically. The relative movement of the non-contactingdetector 21 and the measuring object 101 is done along themeasurement-datum of the relative moving locus (4) depicted in FIG. 12.When the relative movement of the non-contacting detector 21 and themeasuring object 101 reaches to a point on the X'-axis corresponding tothe point P, the non-contacting detector 21 is rotated so as to followthe circular arc (5) by means of the preferable rotation of the turntable 20. The rotation of the turn table 20 is conducted in a state thatthe normal direction of the measuring object 101 and the optical axis ofthe non-contacting detector 21 are coincided and that the distancebetween the measuring surface and the non-contacting detector 21 iswithin a detectable area of the detector. This rotation is continueduntil the non-contacting detector 21 follows the Z'-axis.

In these movements, the measured data by the non-contacting detector 21is written in the memory portion 53 along with data from encoders 45,46, 47 and 48 at predetermined intervals. In ST16, the data stored inthe memory portion 53 is formulated into a surface contour data based onthe measurement-datum. Lastly, in ST 17, the measured data is up-loadedto the data analysis processing unit C. By the data analysis processingunit C, the measured data is shown on a display as the surface contourdata and when optionally designating a point of the surface contour,dimensions, place, angle, radius of a circular arc and the like can beobtained by the least square.

Accordingly, in this embodiment, the surface contour of the standard 100is first measured by relatively moving the non-contacting detector 21and the standard 100, the X'-Z' rectangular spatial coordinate isoriginated in the measurement are based upon the measured data of thestandard 100, and the difference between the spatial coordinates and themechanical coordinates is memorized as the compensation data. As hasbeen explained, first of all, the measuring object 101 is set at apredetermined position in the measuring area, the measurement-datum isoriginated in the measuring area after compensating the profile data ofthe measuring object with reference to the rectangular spatialcoordinates, and the surface contour of the measuring object is nowobtained by a relative movement of the detector 21 and the measuringobject 101 in accordance with the measurement-datum.

The measurement datum is set in the measuring area, so that themeasurement-datum can be corrected easily by the compensation data madeby the measurement of the standard 100. Accordingly, the apparatusaccording to the present invention will not require a precise assemblingand adjustment. The movement system into the X- and Y-axes are onlyrequired to have a function to rotate the non-contacting detector 21 andto keep a repeatable motions precisely. Generally, such repeatablemotions in the apparatus are naturally and easily kept in high level, sothat a less expensive device can be produced.

As the measurement-datum according to the present invention is set inthe spatial measuring area, an optional profile or a function can beused as the measurement-datum, whereby a special measuring object havinga strange profile that the conventional apparatus could not measure nowcan be measured.

As the turn table 20 is secured to the Z-axis slider 18 to rotate aboutthe pivot 34 along the Y-axis and has a non-contacting detector 21thereon so as to coincide the focal point on the central axis of thepivot 34, when measuring a measuring object having a right-angledportion, the non-contacting detector 21 can measure the portion with avertically standing state thereto by being rotated so as to oppose thecenter P of the circular arc. It is known that a high precisionmeasurement requires the alignment of the optical axis of the detector21 with the normal direction of the measuring surface of the measuringobject 101 as much as possible, but the detector 21 according to thepresent invention always keeps a fine state for measurement.Incidentally, if the detector will be a contacting type one, acompensation process for the stylus will not be required.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiments are therefore to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription, and all changes which come within the meaning and range ofequivalency of the claims are therefore intended to be embraced therein.

The measurement-datum is not only limited to be a rectangular spatialcoordinates as described in the embodiments but also to be any line,profile or a combination thereof.

As explained above, the above-explained measurement datum is establishedin the measuring area by compensating the relative movement locuscorresponding to the measuring surface of the measuring object based onthe rectangular spatial coordinates with the compensation data, but itis also available to obtain the profile data by compensating data storedin the memory portion 53 with the compensation data.

The detector used in the above-mentioned embodiments is thenon-contacting detector 21 to measure the surface contour of themeasuring object, however a contacting type detector which contacts withthe surface of the measuring object 101 directly will be also availableto use.

In the embodiments, the measuring object 101 is adapted to move in theX'- and Y'-directions, and the non-contacting detector 21 moves in theZ'-direction. It could be available that at least one of the measuringobject 101 and the non-contacting detector 21 moves the X'- and Z'-axisdirections.

Generally, it is enough to once measure the standard 100 beforeshipment, but a periodical measurement thereof is preferable in view ofpreventing an error which is caused throughout several years.

Incidentally, the preliminary measurement may be omitted before the mainmeasurement, as plural same measuring object is measured after a precisepositioning thereof.

An applicable profile of the measuring object is not limited to that inthe above-mentioned embodiments. When the measuring object 101 has asine-curved profile as shown in FIG. 13, a measurement-datum thereof canbe organized by a combination with straight movement locus (6),(7) and acircular arc movement locus (8) to conduct the relative movement of themeasuring object and the detector.

As has been mentioned above, according to the method and the apparatusfor measuring surface contour according to the present invention, itwill not be require a precise mechanical process and an adjustment toobtain an accurate surface contour data which could not be measured byconventional apparatus.

What is claimed is:
 1. A method of measuring the surface contour of anobject comprising the steps of:taking a plurality of spaced-apart basemeasurements of the surface contour of the object with a detector bytaking said base measurements along an elongated base datum, whereinsaid base measurements represent the distance between the object andsaid base datum; deriving an elongated measurement datum above thesurface of the object based on said base measurements, wherein saidmeasurement datum is at least partially located between said base datumand the object, said derivation of said measurement datum including thestep of storing data representative of the distance between saidmeasurement datum and said base datum; taking a plurality of spacedapart main measurements of the surface contour of the object with saiddetector, wherein said detector is moved along said measurement datumand said main measurements represent the distance between the surface ofthe object and the points on said measurement datum at which said mainmeasurements were made; and generating data representative of thesurface contour of the object based on said main measurements and saidstored data representing said distance between said measurement datumand said base datum.
 2. The method of surface contour measurement ofclaim 1, wherein said detector is attached to a displacement system formoving said detector relative to the object so that said detectortravels along said datums, said displacement system being configured tocause the relative detector/object movement to occur along a mechanicalaxis, and said method further includes the steps of:taking a pluralityof measurements of a standard object with said detector along saiddisplacement system mechanical axis; computing compensating datarepresentative of a difference between a spatial axis separate from saiddisplacement system and said displacement system mechanical axis; andadjusting said measurement datum/base datum distance data with saidspatial axis/displacement system mechanical axis compensating data sothat said generating data representative of the object surface contourcorresponds to contour measurements along said spatial axis.
 3. Themethod of surface contour measurement of claim 2, wherein said detectortakes said measurements of the object without contacting the object. 4.The method of surface contour measurement of claim 1, wherein: saidmeasurement datum is derived so that said measurement datum has at leastone section with a circular profile; and said main measurements aretaken along said measurement datum circular section.
 5. The method ofsurface contour measurement of claim 2, wherein: said measurement datumis derived so that said measurement datum has at least one section witha circular profile; and said main measurements are at taken along saidmeasurement datum circular section.
 6. The method of surface contourmeasurement of claim 2, wherein said displacement system moves theobject relative to said detector along at least one axis to facilitatethe taking of said measurements along said datums.
 7. The method ofsurface contour measurement of claim 2, wherein said displacement systemmoves said detector along at a first axis to facilitate taking saidmeasurements along said datums.
 8. The method of surface contourmeasurement of claim 7, wherein said displacement system is furtherconfigured to move the object relative to said detector along a secondaxis separate from said first axis so that said datums include firstsections oriented along said first and second axes.
 9. The method ofsurface contour measurement of claim 8, wherein said displacement isconfigured to pivot said detector so that said main measurements arealong a measurement datum having a curved profile.
 10. The method ofsurface contour measurement of claim 4, wherein: said displacementsystem is configured to move the object relative to said detector alonga first axis, to move said detector relative to the object along asecond axis separate from said first axis and to pivot said detector;andsaid base measurements are taken along said first and second axes andsaid main measurements taken along said measurement datum circularprofile section are made by pivoting said detector.
 11. The method ofsurface contour measurement of claim 5, wherein: said displacementsystem is configured to move the object relative to said detector alonga first axis, to move said detector relative to the object along asecond axis separate from said first axis and to pivot said detector;andsaid base measurements are taken along said first and second axes andsaid main measurements taken along said measurement datum circularprofile section are made by pivoting said detector.
 12. The method ofsurface contour measurement of claim 11, wherein said detector takessaid measurements of the object without contacting the object.
 13. Amethod of determining the surface contour of an object along a spatialaxis, said method comprising the steps of:measuring a standard objectwith a known contour with a detector that does not contact said standardobject, said detector being connected to a displacement system capableof shifting the relationship between said detector and said standardobject so that said standard object measurements are taken at a numberof selected points along a mechanical axis spaced from a standard objectwherein said standard object measurements represent the distance betweensaid standard object and said mechanical axis at the points on saidmechanical axis at which said measurements were taken; comparing saidstandard object measurements to the known contour of the standard objectso as to produce compensation data representative of the differencebetween said mechanical axis and the spatial axis; taking a plurality ofspaced apart base measurements of the surface contour of the object tobe measured with said detector wherein said initial measurements aretaken along said mechanical axis; deriving a measurement datum above thesurface of the object based on said base measurements wherein saidmeasurement datum is at least partially located between said mechanicalaxis datum and the object and has at least one partially curved section,said derivation of said measurement datum including the step of storingdata representative of the distance between said measurement datum andsaid mechanical axis; taking a plurality of spaced apart mainmeasurements of the surface contour of the object with said detectorwherein said main measurements are taken along said measurement datumincluding said partially curved section thereof, wherein each said mainmeasurement represents the distance between the object and the point onsaid measurement datum at which the main measurement was taken; andgenerating data representative of the object surface contour based onsaid main measurement data, said data representative of said distancebetween said measurement datum and said mechanical axis and saidcompensation data so that said generated data represents the objectsurface contour relative to the spatial axis.
 14. The method of surfacecontour measurement of claim 13, wherein: said displacement system isconfigured to move the object relative to said detector along a firstaxis, to move said detector relative to the object along a second axisseparate from said first axis and to pivot said detector; andsaid basemeasurements are taken along said first and second axes and said mainmeasurements taken along said measurement datum at least one circularprofile section are made by pivoting said detector.
 15. An apparatus formeasuring the surface contour of an object, said apparatus including:abase; a table disposed on said base adapted for receiving the object tobe measured; a displacement mechanism attached to said base and to saidtable for moving said table and the object along a first axis, saiddisplacement mechanism including a drive unit responsive to drivesignals for moving said table and a table position encoder formonitoring the position of said table on said base and configured togenerate table position signals representative of the position of saidtable; a distance measuring detector located above said table, saiddistance measuring detector being configured to measure the distancebetween said detector and the object to produce distance measurementsignals representative of the distance, said distance measuring detectorbeing configured to perform said measurements without contacting theobject; a detector positioning system connected to said base and saiddetector for positioning said detector above said table, said detectorfor moving said detector relative to said table and the object along asecond axis separate from said first axis, said detector positioningsystem including a displacement assembly responsive to detectorpositioning drive signals for selectively positioning said detector anda position encoder for monitoring the position of said detector relativeto said table and configured to generate detector position signalsrepresentative of said position of said detector; a turntable forpivotally securing said detector to said detector positioning unit, saidturntable being configured to pivot said detector around a point, saidturntable having a turntable drive mechanism for selectively pivotingsaid detector in response to application of drive signals thereto andhaving a position detector configured to monitor the pivotal position ofsaid detector that generates turntable position signals representativeof the angular position of said detector; and a control unit connectedto said table displacement system for applying said displacement systemdrive signals thereto and receiving said table position signalstherefrom, to said detector positioning system for applying saiddetector positioning drive signals thereto and receiving said detectorposition signals therefrom, to said turntable for applying saidturntable drive signals thereto and receiving said turntable positionsignals therefrom and to said detector for receiving said measurementsignals therefrom, said control unit being configured to:generate saidtable displacement signals, said displacement mechanism drive signalsand said turntable displacement signals so as to cause said detector tomeasure the contour of the object along a base datum, said base datumextending along said first and second axes; receive a plurality ofmeasurement signals from said detector representative of the distancebetween said detector and the object along said base datum; generate ameasurement datum based on said initial measurement signals, saidmeasurement datum being at least partially closer to the object thansaid base datum and having at least one curved portion and to generatedata representative of the distance between said base datum and saidmeasurement datum; generate said table displacement signals, saiddisplacement mechanism drive signals and said turntable displacementsignals so as to cause said detector to move along said measurementdatum including said at least one curve portion thereof so that saiddetector makes main measurements representative of distances betweensaid measurement datum and the object; receive a plurality of mainmeasurement signals from said detector representative of distancebetween said detector and the object along said measurement datum; andgenerate data representative of object surface contour based on the mainmeasurement signals and said data representative of the distance betweensaid base datum and said measurement datum.
 16. The apparatus of claim15, wherein said table displacement mechanism is configured to move saidtable along a first and third axes wherein said third axis is distinctfrom said first and second axes.
 17. The apparatus of claim 15, whereinthe table is configured to move said object along a horizontal axis andsaid detector positioning system is configured to move said detectoralong a vertical axis.
 18. The apparatus of claim 15, wherein saiddetector is an optical measuring device.
 19. The apparatus of claim 15,wherein said control unit further includes a memory for storingcompensating data representative of differences in distance betweenspatial axes separate from said first and second axes and said basedatum and said control unit generates data representative of the surfacecontour of the object based on said main measurements, said basemeasurements and said compensation data.